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Autism spectrum disorder (ASD) and borderline personality disorder (BPD) are both complex mental health diagnoses that can have a powerful impact on the substance and quality of a person’s life. Both are also widely misunderstood. Sadly, both disorders are frequently stigmatized.

But the similarities don’t end there.

In the past few years, several studies explored how these two disorders overlap. These research efforts document shared symptoms and traits, address diagnostic difficulties, and assess the likelihood that someone diagnosed with one of these conditions will also develop the other.

Defining the Disorders: Autism and Borderline Personality Disorder

Before we discuss the ways that ASD and BPD are similar, let’s take a moment to quickly review the criteria for each condition as established in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5).

Autism Spectrum Disorder

ASD is included in the neurodevelopmental disorders section of the DSM-5.

The diagnostic criteria for this disorder include persistent deficits in social communication and interaction in multiple contexts. These can manifest in the following ways:

  • Inability to engage in typical back-and-forth conversation
  • Poor integration of verbal and nonverbal communication skills
  • Abnormal use of eye contact and body language
  • Diminished likelihood of initiating or responding to social interactions
  • Problems understanding, forming, and maintaining relationships

Autism spectrum disorder is also characterized by restricted and repetitive behavior patterns and interests, such as:

  • Stereotypical and repeated movements or speech
  • Inflexible insistence upon routines and consistency
  • Considerable distress at even minor changes
  • Intense, fixated interests, including preoccupation with unusual objects
  • Excessive or minimal reactivity to sensory inputs such as light, sounds, touch, and temperature

Borderline Personality Disorder

BPD is one of 11 personality disorders in the DSM-5. The primary characteristics of this disorder are pervasive instability and impulsivity, particularly in terms of relationships, self-image, and affect.

A person with borderline personality disorder may exhibit the following symptoms:

  • Making frantic attempts to avoid abandonment, even in the absence of any suggestion it might occur
  • Alternating between idealizing and devaluing their relationships
  • Demonstrating an unstable self-image or sense of self
  • Acting impulsively in areas that can cause personal harm, such as unsafe sex, spending sprees, reckless driving, exorbitant gambling, and substance abuse
  • Making frequent threats or attempts related to self-harm and/or suicide
  • Going through brief but intense periods of elevated anxiety or irritability
  • Experiencing a persistent sense of emptiness
  • Being unable to control or properly direct their anger, which can result in verbal outbursts as well as physical violence
  • Having episodes of paranoia and/or dissociation

Similarities Between Autism Spectrum Disorder and Borderline Personality Disorder

At first glance, it might not look like autism spectrum disorder and borderline personality disorder would be very difficult to differentiate. While both disorders often involve difficulties in relationships with others, the bulk of the diagnostic criteria in the DSM-5 appear to clearly delineate the two.

But when you delve below these surface descriptions, important similarities between ASD and BPD appear.

Empathy & Theory of Mind

In a February 2021 article in the journal Frontiers in Psychiatry, a team led by psychologist Nicoletta Vegni of Niccolò Cusano University in Rome, Italy cited two key areas of overlap between ASD and BPD: lack of empathy and theory of mind.

  • Vegni’s team defined empathy as the ability to discern and understand another person’s state of mind. Mental health experts recognize two types of empathy: cognitive (the ability to recognize emotions in others) and affective (the ability to share the emotions of others).
  • Theory of mind is the ability to understand that other people have beliefs, thoughts, and emotions that differ from one’s own, and then use this knowledge to explain or predict their behaviors.

Multiple studies, the researchers reported, “have uniformly shown that the lack of empathy and theory of mind is an overlapping aspect in BPD and ASD.” However, they noted that the current research does not address similarities or differences between cognitive empathy and affective empathy among people who have these disorders.


A September 2017 study in the journal PLOS One addressed systemizing, which is another similarity between autism spectrum disorder and borderline personality disorder.

Systemizing refers to a desire to build or analyze rules-based patterns. As described in an August 2018 article on the Embrace Autism website, systemizing can manifest in the following ways among people who have ASD:

  • Insisting on eating the same food every day
  • Developing an obsession with calendars or timetables
  • Requiring objects to be arranged in a particular order
  • Watching the same video multiple times

The team that conducted the PLOS One study reported that “people with BPD also report elevated systemizing relative to controls, without a statistically significant difference between them and the [autism spectrum disorder] groups.”

The researchers noted that systemizing may be a subconscious attempt to compensate for emotional instability. It is also consistent with a distaste for change, which can be symptomatic of both autism spectrum disorder and borderline personality disorder.

Diagnostic Challenges

In February 2023, Embrace Autism published an article that addressed the prevalence of misdiagnoses involving autism spectrum disorder and borderline personality disorder.

The authors of this article, Natalie Engelbrecht, ND, RP, and Debra Bercovici, PhD., noted that many people who are diagnosed with ASD later in life have previously been incorrectly diagnosed with BPD.

They theorized that this may be due to the fact that many behaviors exhibited by people with autism spectrum disorder can easily be misinterpreted as symptoms of BPD.

Autism and Borderline Personality Disorder: Overlapping Symptoms

  • Many people with ASD have difficulty maintaining relationships, which can cause them to develop a fear of abandonment. But when try to avoid future abandonment, this can look like a symptom of borderline personality disorder.
  • Intensity and inflexibility, characteristics of autism spectrum disorder, can cause people with ASD to have intense but brief relationships, also a symptom of BPD.
  • Many people with autism spectrum disorder have an unstable self-image, a symptom of borderline personality disorder. But for those with ASD, their self-image challenges aren’t intrinsic. They often reflect the negative feedback and confusing signals they receive from others.
  • People with ASD may have “meltdowns” when exposed to levels of sensory input that exceed their capacity to process. To someone who doesn’t realize the cause of these meltdowns, they can appear like an anger management problem, a symptom of borderline personality disorder.
  • Engelbrecht and Bercovici reported that as many as 70% of people with autism spectrum disorder also have attention-deficit/hyperactivity disorder (ADHD). One of the characteristics of ADHD is impulsivity, which can also be a symptom of BPD.

To accurately diagnose a person with either ASD or BPD, Engelbrecht and Bercovici advised, clinicians need to evaluate why a person acts a certain way, instead of focusing solely on the actions themselves.

“When clinicians incorrectly diagnose an individual with BPD instead of autism, they often overlook the underlying cause of these outward behaviors,” they wrote. “This happens most in autistics who mask and camouflage such that they ‘don’t look autistic’ according to the stereotype.”

Co-Occurring ASD and BPD

As Engelbrecht and Bercovici reported, many people who have autism spectrum disorder are misdiagnosed with borderline personality disorder. In other cases, people with BPD are misdiagnosed with ASD.

Given the similarities between these two disorders, is it possible for someone to have both at the same time?

According to an article in the March-April 2023 issue of the Harvard Review of Psychiatry, co-occurring ASD and BPD definitely happens.

This article noted that about 4 percent of people with borderline personality disorder also have autism spectrum disorder. Another study suggested that about 3 percent of people with ASD also have BPD.

  • The World Health Organization (WHO) reports the global rate of autism spectrum disorder is about 1%.
  • This means that about 75 million people across the planet have ASD.
  • If 3% of these individuals also have borderline personality disorder, that means more than 2.2 million people worldwide have co-occurring ASD and BPD.
  • Applying these estimates to the United States means that, theoretically, about 100,000 people in the U.S. have both autism spectrum disorder and borderline personality disorder.

Compared with many other mental health challenges, co-occurring ASD and BPD is relatively rare. But for the millions of people who have both conditions – as well as for the unknowable number misdiagnosed with one or the other – the ability of treatment professionals to recognize the similarities between autism spectrum disorder and borderline personality disorder can be life-changing.